The present invention relates generally to medical instrumentation for implanting medical devices. More particularly, the invention relates to an instrument guide and holder assembly that can be used in conjunction with orthopedic plate systems.
In the art of orthopedic fixation, it has become common for surgeons to utilize fixation plates for the treatment of spinal disorders including spinal anomalies, spinal injuries, disc problems, and bone problems. Indeed, within the past several years, the use of fixation plates for the treatment of spinal disorders or for fusion of vertebrae has grown considerably, and spinal plates have found increased use and desirability in the cervical spine as well.
As adequately described by Dr. Howard S. An and Dr. Jerome M. Cotler in the publication entitled Spinal Instrumentation, the upper cervical spine can be approached either anteriorly or posteriorly, depending upon the spinal disorder to be treated. This text discusses the fact that severe complications associated with procedures involving the upper cervical spine can be catastrophic, including injuries to the brain stem, spinal cord, or vertebral arteries, not to mention damage to the esophagus. These complications for upper cervical spine procedures are in addition to the normal complications associated with exposure and fusion of the cervical spine, implantation of a spinal fixation plate, and general disturbance of the spine.
In procedures involving the cervical spine, additional difficulties are encountered as a direct result of the small space in which the surgeon has to operate. When the upper cervical area is dissected, surgeons often find it difficult to maneuver because dissection is intimately close to vital neural, vascular, and visceral structures. As a result, surgeons have little room to operate, and even less room to manually position bone implant structures. Couple this with the fact that the surgeon typically seeks to minimize the time in which the spine is exposed, and the result is a need for bone implant assemblies and their related medical instrumentation to allow for rapid and accurate placement of the bone implant.
In certain procedures requiring variable angle fixation (that is, insertion of fasteners that are allowed to have varying angles of entry to allow settling and movement in situ) surgeons sometimes have difficulty maintaining consistency when performing multiple operative techniques through a given variable through-hole. For instance, when attempting to drill, tap, and insert a variable angle screw in a bone implant through an instrument guide, slight movements in the instrument guide that occur between or during these separate operative techniques can result in misaligned threads, stripped threads, and overall generalized weakened fastening. As a result, the need exists for an instrument guide that can lock the variable cannula in place to facilitate the multiple operative techniques that must be performed therethrough.
Several prior art devices have attempted to provide an instrument and/or a plating system to accurately and quickly locate a bone plate at the proper location on the target bone. Many systems employ the use of multiple component devices: a device that acts as a guide to drill the holes; a device to tap the bone via the hole; and a device that inserts the screw into the plate and bone through the holes created by the first two devices. Using multiple instruments can be time-consuming and aggravating to the surgeon. In addition, inserting and removing separate devices in the small exposed surgical area increases the likelihood of damage to the surrounding tissue.
Additionally, many prior art devices lack an appropriate mechanism to releasably secure the instrument guide to the implant. Problems related to these prior art devices generally fall into two categories: those that provide no mechanism for securing the guide to the implant, and those that provide a mechanism that gives too much of a positive locking force. In addition, these instruments in the prior art typically are provided with handles that are offset at some distance from the longitudinal axis of the screw holes. Unfortunately, these systems are cumbersome, time-consuming, and provide very little visual feedback for the surgeon to assist in the procedure.
Therefore a need exists for a medical instrument guide that can rapidly, adequately, and safely locate a bone implant at the desired area. In addition, the need exists for a medical instrument that facilitates all the surgical or operative procedures that a surgeon may employ in implanting a plate, including puncturing, drilling, tapping, verifying hole depth, and fixating a bone screw through a bone plate into a bone that can be done with one versatile instrument. Ideally, these should be capable of being done using a single instrument that need not be removed from the dissected area until these procedures have been completed.